Piston internal combustion engine with cylinder liner secured directly at the cylinder head

ABSTRACT

A piston internal combustion engine with a cylinder liner secured directly at the cylinder head by means of a mounting collar engaging in an annular groove of the cylinder head; the collar is adjoined externally and internally by annular sealing surfaces provided at the liner end face; the inner flank of the collar serves the purpose of centering the liner while the outer flank thereof serves the purpose of fastening the liner in the cylinder head.

United States Patent Hoch [151 3,685,399 1 Aug. 22, 1972 PISTON INTERNAL COMBUSTION ENGINE WITH CYLINDER LINER SECURED DIRECTLY AT THE CYLINDER HEAD Manfred Hoch, Berlin, Germany Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim, Germany Filed: April 20, 1970 Appl. No.: 30,083

Inventor:

Assignee:

Foreign Application Priority Data April 23, 1969 Germany ..P 19 20 704.6

US. Cl. ..92/171, 123/193 CH Int. Cl. ..Fl6j 11/04 Field of Search ..92/169, 171; 123/193 CH; 285/331, 381, 390; 292/300; 220/39, 40

References Cited UNITED STATES PATENTS 12/1960 Rogers ..92/171 4/1946 Cole ..285/381 1,825,769 10/1931 Barbou ..285/381 1,260,861 3/1918 Bie ..92/171 1,227,240 5/1917 Bie ..92/171 1,573,103 2/1926 Tomlinson ..285/331 1 ,5 75,638 3/ 1926 Pochobradsky ..92/ l 7 l FOREIGN PATENTS OR APPLICATIONS 403,077 3/1943 Italy 123/ 193 CH 357,837 10/1931 Great Britain ..123/193 CH Primary Examiner-Martin P. Schwadron Assistant Examiner--R. H. Lazarus Attorney-Craig, Antonelli and Hill 57 ABSTRACT 16 Claims, 3 Drawing Figures PATENTEDAUBZZISTZ 3.685.399

HGI

RED HOCH BY Mu Jam.

2411/ ATTORNEYS PISTON INTERNAL COMBUSTION ENGINE WITH CYLINDER LINER SECURED DIRECTLY AT THE CYLINDER HEAD The present invention relates to a piston internal combustion engine with a cylinder liner secured directly at the cylinder head.

With known internal combustion engines of this type, the cylinder liner is provided with a relatively long thread at its outer surface, by means of which it is threaded into a counter-thread in a cylindrical recess of the cylinder head. The part of the combustion space which thermally is loaded strongest, is disposed in the cylinder head, difficult to cool, with this type of securing. The sealing between the cylinder liner and the cylinder head is possible only by the relatively small end surface of the cylinder liner. Leakage gases penetrate into the thread and cause a deterioration in the heat transfer between the cylinder liner and the cylinder head within the area of the combustion space. A differing heat expansion of cylinder liner and cylinder head results therefrom which, during the operation, leads to a play enlargement in the thread and finally to a loosening of the cylinder liner. A further disadvantage of this type of construction is the inaccurate centering of the cylinder liner in the cylinder head by a thread, especially as the latter is relatively long. Unfavorable in their effect are with this type of fastening, the cross forces stemming from the piston which have to be absorbed in the first instance by the thread and therefore strongly load and stress the same. Finally, the manufacture of the long threaded section at the cylinder liner and at the cylinder head increases the cost of the manufacture.

It is the aim of the present invention to avoid these disadvantages and to provide a thermally favorable and reliably sealing connection between a cylinder liner and the cylinder head. This is realized by a flange at the cylinder liner whose end face is provided with an annularly shaped inner sealing surface and with an annularly shaped outer sealing surface, between which is arranged a mounting collar that engages in an annular groove of the cylinder head and whose inner flank serves the purpose of centering and whose outer flank serves the purpose of fastening in the cylinder head. It

is thereby favorable if the mounting collar according to the present invention has approximately a square crosssection which produces a good centering and a short thread with sufficient rigidity. According to a further feature and construction of the present invention the cylinder liner may be secured at the cylinder head in an advantageous manner by a threaded connection or by a shrunk connection or press-fit connection.

The internal combustion engine according to the present invention entails additionally the following considerable advantages: the cylinder liner can be circumcirculated over its entire length by a cooling medium. The securing thread is disposed above the upper boundary surface of the combustion chamber and is therefore thermally relieved. The piston cross forces do not become effective on the thread since they are absorbed by the centering means. During tightening of the threaded connection of the cylinder liner, a part of the torque is applied for the build-up of the friction connection between the sealing surfaces at the bottom side of the cylinder head. The seal is improved thereby and the loosening of the cylinder liner avoided. In addition to the easy machining possibilities of the flat bottom side of the cylinder head, the manufacture is thereby considerably simplified in that all of the parts can be finish-machined prior to the assembly so that after-finishing operations are dispensed with.

Accordingly, it is an object of the present invention to provide a piston internal combustion engine with a cylinder liner secured directly at the cylinder head which avoids by simple means the afore-mentioned shortcomings and drawbacks encountered in the prior art constructions.

Another object of the present invention resides in a cylinder liner construction secured directly at the cylinder head of a piston internal combustion engine which assures a proper seal between cylinder liner and cylinder head, precludes thereby the interaction of leakage gases on the threaded connection and thus avoids any subsequent loosening of the liner.

A further object of the present invention resides in a piston internal combustion engine with a cylinder liner directly secured at the cylinder head which not only assures a proper centering of the liner but also relieves the threaded connection from the function of absorbing the piston cross forces.

Still another object of the present invention resides in a cylinder liner directly secured at the cylinder head of a piston internal combustion engine which greatly simplifies the manufacture and assembly while eliminating the need for after-finishing operations.

These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein:

FIG. 1 is a longitudinal cross-sectional view through a cylinder liner threaded into a cylinder head in accordance with the present invention; and

FIG. 2 is a partial cross-sectional view, on an enlarged scale, illustrating the details encircled in dash and dot lines in FIG. 1. I

FIG. 2A is a further schematic cross-sectional view corresponding to FIG. 2, but showing the thread and groove structure in different form.

Referring now to the drawing wherein like reference numerals are used throughout the two views to designate like parts, reference numeral 11 designates the cylinder head of a liquid-cooled piston internal combustion engine of otherwise conventional construction, which is provided with gas channels 12 and cooling channels 13 in the cylinder head 11. The flat bottom side 14 of the cylinder head 11 is provided with an annular groove 16 coaxial to the cylinder axis 15; an internal thread 18 is cut into the outer side 17 of the annular groove 16. The inner side 19 of the annular groove 16 is constructed as seating surface.

A wet cylinder liner 20 is threadably connected at the cylinder head 11 in such a manner that a sealing connection results without any further structural parts. For this purpose, the cylinder liner 20 passes over at its one end into a flange 21. The end face 22 (FIG. 1) of the flange 21 is provided with a fine-finished, annularly shaped inner sealing surface 23 (FIG. 2) which seals with respect to the combustion gases, and with an annularly shaped outer sealing surface 24 (FIG. 2) which seals with respect to the combustion gases, and with an annularly shaped outer sealing surface 24 (FIG. 2) which seals with respect to the cooling liquid. The sealing surfaces 23 and 24 abut against the bottom side 14, of the cylinder head 1 1, which is also precision or finefinished. An upright mounting collar 25 with approximately square cross-sectional surface is arranged between the sealing surfaces 23 and 24. The inner flank 26 of the collar 25 is constructed as seating surface corresponding to the inner side 19 of the annular groove 16 and has the purpose to center the cylinder liner 20 in the cylinder head 11. The outer flank 27 is provided with an external thread 28 which is threaded into the internal thread 18 of the annular groove 16. The minor radial play existing between the outer thread 28 and the inner thread 18 prevents the jamming of this threaded connection during assembly. A ring-shaped groove 29 between the outer thread 28 and the flange 21 of the cylinder liner 20 as well as a free space 30 over the bottom 31 of the annular groove 16 of the cylinder head 11 enable a completely satisfactory abutment of the sealing surfaces 23 and 24 against the bottom side 14 of the cylinder head 11. See FIGS. 2 and 2A for a schematic showing of the relationship between the threads, sealing surfaces, and groove 29. A further seal between the cylinder liner 20 and the cylinder head 11 results from the seat of the seating or fitting surfaces at the inner flank 26 of the collar 25 and the inner side 19 of the annular groove 16. The measures in accordance with the present invention thus produce a triple seal, disposed in different planes, of the combustion space at the connecting place of cylinder head 11 and cylinder liner 20.

While I have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art. For example, instead of being secured by a threaded connection as illustrated in the described embodiment, the cylinder liner may be secured at the cylinder head also by a slip joint or shrunk connection. Additionally, the present invention is suited both for liquid-cooled as also for aircooled piston internal combustion engines. Consequently, I do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

I claim:

1. A piston internal combustion engine comprising: a cylinder head, a cylinder liner, and connecting means including an annular collar on an end face of said liner engaging in a corresponding annular groove in said head, said liner having inner and outer annularly shaped sealing surfaces positioned respectively inside and outside of said collar, said head having inner and outer annularly shaped sealing surfaces positioned respectively inside and outside of said groove such that said sealing surfaces on said head engage with the corresponding sealing surfaces on said liner for sealing the groove and collar connecting means from all engine fluids andgases, an inner flank of said collar engaging a corresponding wall of said groove for centering the 4 Slfifll'iilifii? fiiiin fi rfiififiingill' connecting means with respect to corresponding fastening means provided on a corresponding wall of said groove, the arrangement of said fastening means on the outer flank of said collar effectively insulating said connecting means from the thermal stresses inside of said liner.

2. A piston internal combustion engine according to claim 1, characterized in that said collarhas an approximately square cross-section.

3. Apiston internal combustion engine according to claim 2, characterized in that the cylinder liner is connected at the cylinder head by a threaded connection.

4. A piston internal combustion engine according to claim 2, characterized in that the cylinder liner is secured at the cylinder head by a shrink fit.

5. A piston internal combustion engine. according to claim 1, characterized in that the inner surface of the annular groove of the cylinder head and the inner flank of said collar are constructed as complementary seating surfaces.

6. A piston internal combustion engine according to claim 5, characterized in that the outer surface of the annular groove in the cylinder head and the outer flank of said collar are constructed as complementary mutually engaging surfaces.

7. A piston internal combustion engine according to claim 6, characterized in that said last-mentioned mutually engaging surfaces form a threaded connection.

8. A piston internal combustion engine according to claim 6, characterized in that said last-mentioned mutually engaging surfaces form a shrink fit.

9. A piston internal combustion engine according to claim 6, characterized in that said collar has an approximately square cross-section.

10. A piston internal combustion engine according to claim 1, characterized in that the cylinder liner is connected at the cylinder head by a threaded connection.

l l. A piston internal combustion engine according to claim 1, characterized in that the cylinder liner is secured at the cylinder head by a shrink fit.

12. A piston internal combustion engine according to claim 1, characterized in that the outer surface of the annular groove in the cylinder head and the outer flank of said collar are constructed as complementary mutually engaging surfaces.

13. A piston internal combustion engine according to claim 12, characterized in that said mutually engaging surfaces form a threaded connection.

14. A piston internal combustion engine according to claim 12, characterized in that said mutually engaging surfaces form a shrink fit.

15. A piston internal combustion engine according to claim 7, characterized in that a groove is provided in a lower portion of the outer flank of said collar, said groove forming an interruption in the thread means on 

1. A piston internal combustion engine comprising: a cylinder head, a cylinder liner, and connecting means including an annular collar on an end face of said liner engaging in a corresponding annular groove in said head, said liner having inner and outer annularly shaped sealing surfaces positioned respectively inside and outside of said collar, said head having inner and outer annularly shaped sealing surfaces positioned respectively inside and outside of said groove such that said sealing surfaces on said head engage with the corresponding sealing surfaces on said liner for sealing the groove and collar connecting means from all engine fluids and gases, an inner flank of said collar engaging a corresponding wall of said groove for centering the cylinder liner with respect to said head, an outer flank of said collar including fastening means for forming the connecting means with respect to corresponding fastening means provided on a corresponding wall of said groove, the arrangement of said fastening means on the outer flank of said collar effectively insulating said connecting means from the thermal stresses inside of said liner.
 2. A piston internal combustion engine according to claim 1, characterized in that said collar has an approximately square cross-section.
 3. A piston internal combustion engine according to claim 2, characterized in that the cylinder liner is connected at the cylinder head by a threaded connection.
 4. A piston internal combustion engine according to claim 2, characterized in that the cylinder liner is secured at the cylinder head by a shrink fit.
 5. A piston internal combustion engine according to claim 1, characterized in that the inner surface of the annular groove of the cylinder head and the inner flank of said collar are constructed as complementary seating surfaces.
 6. A piston internal combustion engine according to claim 5, characterized in that the outer surface of the annular groove in the cylinder head and the outer flank of said collar are constructed as complementary mutually engaging surfaces.
 7. A piston internal combustion engine according to claim 6, characterized in that said last-mentioned mutually engaging surfaces form a threaded connection.
 8. A piston internal combustion engine according to claim 6, characterized in that said last-mentioned mutually engaging surfaces form a shrink fit.
 9. A piston internal combustion engine according to claim 6, characterized in that said collar has an approximately square cross-section.
 10. A piston internal combustion engine according to claim 1, characterized in that the cylinder liner is connected at the cylinder head by a threaded connection.
 11. A piston internal combustion engine according to claim 1, characterized in that the cylinder liner is secured at the cylinder head by a shrink fit.
 12. A piston internal combustion engine according to claim 1, characterized in that the outer surface of the annular groove in the cylinder head and the outer flank of said collar are constructed as complementary mutually engaging surfaces.
 13. A piston internal combustion engine according to claim 12, characterized in that said mutually engaging surfaces form a threaded connection.
 14. A piston internal combustion engine according to claim 12, characterized in that said mutually engaging surfaces form a shrink fit.
 15. A piston internal combustion engine according to claim 7, characterized in that a groove is provided in a lower portion of the outer flank of said collar, said groove forming an interruption in the thread means on said collar means.
 16. A piston internal combustion engine according to claim 7, characterized in that said mounting collar extends upwardly with respect to both of said sealing surface means, an amount less than the depth of said annular groove. 